lkml.org 
[lkml]   [2006]   [Jan]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [patch 5/6] mm: simplify vmscan vs release refcounting


On Thu, 19 Jan 2006, Nick Piggin wrote:
>
> The VM has an interesting race where a page refcount can drop to zero, but
> it is still on the LRU lists for a short time. This was solved by testing
> a 0->1 refcount transition when picking up pages from the LRU, and dropping
> the refcount in that case.

Heh. Now you keep the count offset, but you also end up removing all the
comments about it (still) being -1 for free.

And your changelog talks about "atomic_inc_not_zero()" even though the
code actually does

atomic_add_unless(&page->_count, 1, -1);

which makes it pretty confusing ;)

I also think it's wrong - you've changed put_page_testzero() to use
"atomic_dec_and_test()", even though the count is based on -1.

So this patch _only_ works together with the next one, and is invalid in
many ways on its own. You should re-split the de-skew part correctly..

Linus
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2009-11-18 23:46    [W:0.057 / U:0.076 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site